Week - 4 - 2D meshing for Plastic components

BOTTLE CAP CHALLENGE

AIM:

• In this challenge the given model is Plastic Bottle Cap, we are going to create the 'FE model' for this component using the 'ANSA preprocessing tool'.

CHALLENGE EXPECTATION:

• Check for the geometrical errors and take the mid surface CAD model, and Mid surface has to be extracted.
• The extracted Mid surface has to be meshed with the proper Quality mesh flow under given quality criteria.
• PID and Thickness assignment has to be done for all the mid surfaces.

PROPERTIES OF THE COMPONENTS:

• Materials which is having less than or equal to 6mm can be meshed with 2D Meshing.
• In 2D Meshing, we can classify the materials into two types.
  
  • Sheet Metal Component
  • Plastic Component

• The material which is having Linear Thickness throughout the Body is known as 'Sheet metal'
• The material which is having Non Linear Thickness is 'Plastic Material'.

PROCEDURE:

• CAD SET UP
  • CAD Geometry
  • Model Clean Up
• CAD MODELING
  • Meshing
• FINAL CHECK
  
  • Maintaining proper Mesh
  • Assigning Thickness to Mid.surface

PREPERATION OF MODEL FOR MESHING: (Part -1)

• I used to check the existing PID’s in the ‘Property Card', in this Bottle cap model there is only one PID was there.

Steps to be followed in Begining:

• Import the downloaded geometry using File manager and then we have to set 'Cons Resolution' for the parent geometry, It is present in (Mesh module/Perimeters Group/Length)
• Next step is Orient (Topo module/Faces group/Orient)

• This is our Bottle Cap model.

TOPOLOGY CLEAN UP: (Part - 2)

• Now it is time to Geometry Cleanup.
• Before start meshing Geometry Check is necessary, because in Original CAD geometry there might be some errors in cons.

• In our 'Bottle Cap Model' only two errors were present when perform the geomentry check.
• We can find the option (Tools/Checks/Geometry) here.
• In ANSA there is an option called 'AUTO FIX', i used this function to fix my errors, because it saves more time.

THICKNESS CHECK

• We can see it clearly this BOTTLE CAP model has Non uniform thickness so we can consider this is Plastic Component.

MID SURFACE CREATION: (Part - 3)

• We have prepared geometry. Next step is creating the mid-planes

There are Two methods to create Mid plane

• Manual Method
• Automatic Method

• In this model i used the Manual mid.surface to create the Mid Surface, using the Option (Topo Module/Faces Group/Mid.surface/Casting)
• The Reason I go with the Auto method because this model has different thickness in various areas, so the mid surface extraction save my time a Bit in auto method
• On the 'Single middle mouse button' confirmation the mid surface creation is done easily.

BEFORE CREATING MIDSURFACE

STEPS TO FOLLOW BEFORE MESHING:

• We have set the Quality criteria and mesh Parameters properly as per the given requirement, because when we use the 'CASTING' option, the mesh also be Generated automatically.

AFTER CREATING MIDSURFACE

• The Mid Surface is Created by 'CASTING' option so the PID has assigned to it automatically.
• Here also it saves our efforts to creating it by manual.

EXTRACTED MID SURFACE PID

• As we can clearly see this mid.surface that created by the 'CASTING' is not that much good.
• Some areas are not properly aligned compare to the 'PARENT GEOMETRY'
• So it is our responsibility to clean it up and make it proper.

HERE ARE THE SOME EXAMPLES OF DISTORTED AREAS OF OUR CASTING RESULT:

• These areas can not capture during CASTING operation, here some features and some fillet areas not properly created.
• Now it is time for cleaning with the help of the ALIGN MANAGER.

ALIGN MANAGER FUNCTIONS:

• These are the main aeas of Align manager.

MISSED TEETH CAPTURING

• To Capture this feature I use the 'Middle curve' option to create it as a Reference of Parent Geometry. (Topo module/Curves Group/Middle)

Steps showed in the above Image

• Step 1- Middle Curve Creation using middle curve option
• Step 2- Project the curve in the middle surface using (Mesh module/Shell mesh group/Project)
• Step 3- Fill option can be used to create a new surface with help of the projected line and the middle curve
• Step 4- The Newly created shells can see, with the help of Align Manager the definition has given.

• After creating the one teeth the Transfrom/Rotate option used to capture the other features as well.
• In total 26 tooth has been created.

FINAL CHECKING OF MESH: (Part - 4)

• Once we done with the clean up and corrections of the 'CASTING RESULT', need to work on the OFF ELEMENTS and the MESH FLOW.
• Some areas are not meet the 'Quality Criteria', where the areas Triple Cons closely present in the model, Elements has failed .

• In the Above picture, the critical areas are mostly off elements were present.
• This was the challenging task for me, I managed to get the better result as much as I can.

HERE IS THE BEFORE & AFTER RESULT OF OFF ELEMENTS:

• This is the data in the above picture that i receive after I corrected the Distorted casting Result.
• In this window the Off elements percentage was high.

• After dealing with Off elements and mesh flow, this is the Final outcome of the Bottle Cap.

ASSIGNING THICKNESS TO THE MID SURFACE:

• Thickness has been assigned to the different thickness areas individually, using (Mesh module/Grids/Thickness/Convert)

RESULT OUTCOMES:

• Finally achived Trias with 2.34% and OFF Elements with 0.14%
• Good Mesh flow, no trias touching on the Circle and no trias touching the Free end.
• No Rottating Quads keep maintained, No Opposite Trias are present in the FE model.
• No any other Feature Lines missed while meshing.
• Missed Ribs, Thread and Teeth has been captured properly as per the Parent Geometry Reference.

CONCLUSTION AND LEARNING OUTPUTS:

• On the conclustion of this Bottle cap model, it was a Quiet a challenging one, when completing this model, I learned new commands and how they are helpful to achieve good meshing.
• The new method of Mid surface/Casting option learned in this challenge.
• It gives the confidence to meet any complicated Models can be easily face it.
• Especially the Align manager and 'Mesh module/Grids/Align options' are the interesting things to learn from this challenge.